Publisher Summary This chapter provides an overview of the specific security issues that affect MPLS and describes some of the techniques that have been developed to address those issues. Many of the specific issues affecting MPLS arise from the use of a label-swapping forwarding paradigm, which changes the playing field somewhat relative to the datagram model of IP. In addition, MPLS has its own set of control protocols, which also need to be protected against certain attacks. One of the types of attacks—if an unauthorized device is able to send MPLS signaling messages then it might be able to create unauthorized LSPs. Various types of Denial of Service (DoS) attack can be launched using the MPLS control plane, much like many other control plane protocols such as CPU cycles, and memory can be consumed just by opening LDP sessions or by sending RSVP-TE messages. Many attacks on the data plane are common across all types of packet network. MPLS networks can be subject to observation of data packets (resulting in loss of confidentiality), modification of data packets, insertion or deletion of data packets, replay attacks, and traffic pattern analysis.